Apparatus for machining slots in apertures

Abstract

A portable device (10) for excising an axial slot (8) into the boundary surface (16) of an aperture (15). The device (10) includes a guide (11), a machining implement (12) and a power source (13). The guide (11) has proximal and distal ends (19 and 20) with an exterior configuration including at least a horn surface (26) and a transitional surface (30). A reaction flange (21) extends radially outwardly from the proximal end (19) of the guide (11). A slideway (35) extends longitudinally within the guide (11), and a tracking channel (36) extends radially outwardly from the slideway (35) to penetrate the guide (11) along the axial extent thereof. The machining inplement (12) includes a drive shaft (40) that is axially translatable within the slideway (35) and a plurality of teeth (45) that are progressively stepped with the shortest tooth (45 A) being located in proximity in the medial portion (46) of the shaft (40) and with the highest tooth (45N) being located in proximity to the distal end (48) of the shaft (40). The power source (13) is connected to, and selectively protracts and retracts, the shaft (40). When the machining implement (12) is protracted relative to the guide (11) the assembled combination can be operable received through an aperture (15) in a workpiece (14) to excise a slot (81) in the boundary surface (16) of the aperture (15) with access to only one side of the workpiece (14).

I claim: 
     
       1. A portable cutting apparatus for excising an axial slot into the boundary surface of an aperture in a workpiece, said cutting apparatus comprising: a power source;   a guide means having a sleeve-like body portion with proximal and distal ends relative to said power source;   a reaction flange extending radially from the proximal end of said guide means to engage the workpiece and effect longitudinal stabilization between the cutting apparatus and the workpiece;   a locating pilot located at the intersection of said reaction flange and said guide means;   a radially outwardly directed locating surface presented from said locating pilot to engage the aperture in the workpiece and effect radial orientation of the cutting apparatus relative to the workpiece;   a slideway extending longitudinally within the guide means and opening through the proximal and distal ends thereof;   a tracking channel extending radially outwardly from said slideway to penetrate said guide means along the axial extent thereof;   a drive shaft received for longitudinal translation within said slideway;   said drive shaft also having proximal and distal ends relative to said power source with a medial portion therebetween;   said proximal end of said drive shaft operably attached to said power source;   a broach;   said broach having a base plate with a plurality of teeth extending outwardly of said base plate;   said base plate being fully supported by, and being demountably secured to, said drive shaft from between approximately the medial portion of said drive shaft to approximately the distal end thereof;   said broach being oriented such that said teeth extend radially outwardly through said tracking channel;   said teeth being progressively stepped with the roughing tooth having the least radial dimension being located in proximity to the medial portion of said drive shaft and with the finishing tooth having the greatest radial dimension located in proximity to the distal end of said drive shaft;   a horn portion presented from said guide means to engage a sufficient portion of the aperture to stabilize said broach and said drive shaft relative to the workpiece;   said horn portion being longitudinally truncated to provide a shelf formed as the base of the sector removed by truncation;   a transition portion extending between the distal end of said guide means and said horn portion thereof to present a generally conical exterior surface;   said shelf extending the full axial extent of said guide means to feather into generally conical exterior surface of said transition portion; and   said tracking channel opening through said shelf such that said shelf truncates said guide means on both sides of said tracking channel.   
     
     
       2. A portable cutting apparatus, as set forth in claim 1, wherein the projected dimension of the side elevational profile of said guide means at the distal end thereof is such that the effective radial dimension of said guide means opposite said tracking channel plus the diameter of said driven shaft, including the height of said cutting tooth extending through said tracking channel at the axial location where the effective radial dimension of said guide means is being considered, is less than the corresponding diameter of the boundary surface for the aperture through said workpiece. 
     
     
       3. A portable cutting apparatus, as set forth in claim 2, wherein the dimensions comprising the elevation profile of said guide means in proximity to the proximal end thereof being such that the radial dimension of said guide means opposite said tracking channel plus the diameter of said drive shaft, including the height of said cutting teeth extending through the tracking channel opposite the location where the effective radial dimension of the guide means is being considered, is greater than the diameter of the aperture to be slotted.